Modularly Evolved 2-AminoDMAP/Squaramides as Highly Active Bifunctional Organocatalysts in Michael Addition
作者:Murat Işık、M. Yagiz Unver、Cihangir Tanyeli
DOI:10.1021/jo5022597
日期:2015.1.16
We report a new family of chiral bifunctional acid/base type organocatalysts, 2-aminoDMAP/Squaramides, which are proved to be highly active (1 mol % cat. loading) promoters in conjugate addition of dibenzoylmethane to various trans-β-nitroalkenes. Steric demand of the catalysts was clearly seen by a set-by-set modulation of the squaramide unit through electronic and steric factors. The synergistic
Synthesis of Chiral Tertiary Amine–Thioureas Based on Spirobiindane and Application in Catalytic Asymmetric Michael Addition Reaction
作者:Zhao Han、Xufeng Lin
DOI:10.1055/s-0039-1691643
日期:2020.4
A series of novel chiral bifunctional tertiary amine–thioureas based on spirobiindane were designed and synthesized as organocatalysts. One of these catalysts was shown to promote the asymmetric Michael addition reaction of 1,3-diphenylpropane-1,3-dione to nitroolefins, affording the desired products in good yields (up to 95%) and enantioselectivities (up to 98% ee).
A series of novel carbohydrate-derived thioureas were synthesized and examined as catalysts for the asymmetric Michael addition of symmetrical 1,3-dicarbonyl compounds, including dimethyl malonate, to several trans-β-nitrostyrenes. High enantioselectivities (up to 94% ee) as well as high yields (up to 98%) were attained using a bifunctional organocatalyst bearing a cinchona-based alkaloid unit.
Disclosed is a process of carrying out a Michael reaction with recovery of the catalyst, where a compound of formula (1):
is reacted with a compound of formula (2):
in the presence of a catalyst of formula (4):
where the compounds of formulae (1) and (2) undergo a Michael reaction.
Highly enantioselective Michael addition of 1,3-dicarbonyl compounds to nitroalkenes catalyzed by designer chiral BINOL–quinine–squaramide: efficient access to optically active nitro-alkanes and their isoxazole derivatives
A chiral BINOL-quinine-squaramide has been identified as the best catalyst for the asymmetric Michael addition of nitroalkenes to 1,3-dicarbonyl compounds. A series of chiral nitroalkanes were prepared with approximately >99% ee. Furthermore, the methodology was applied successfully to the synthesis of enantiomerically pure isoxazoles derivatives (>99% ee). (C) 2013 Elsevier Ltd. All rights reserved.